With the development of air conditioning technologies, a variable frequency air conditioner has been applied widely in the industry. However, in an outdoor electrical control system of the variable frequency air conditioner, heat production of a frequency conversion module is large, which limits a high frequency operation of a compressor under a high temperature environment. A heat dissipation mode of the electrical control system which is mostly used currently is that a metal cooling fin dissipates heat through air convection. However, under the outdoor high temperature environment, the heat dissipation mode has a poor effect, and it is a common practice to reduce the heat production of the electrical control system by decreasing an operation frequency of the compressor, so as to ensure that the air conditioner operates normally, thereby greatly affecting a cooling effect of the variable frequency air conditioner when the outdoor ambient temperature during use is high and affecting the use comfortability of an user. In the existing art, the heat dissipation technology for the electrical control system of an outdoor unit through a low temperature coolant has problems that condensation water may be produced or the temperature of the electrical control system of the outdoor unit drops too much, which affects use reliability and safety of the electrical control system. For example, in Chinese patent publication No. CN102844980, titled “Refrigeration Apparatus”, not only a product is hard to be formed due to a complicated refrigeration system design, poor processability, complex program control and high cost, but also an energy efficiency loss is great because in a refrigeration circulation, a throttled part of a coolant may absorb heat of a power device.